Voice synthesis on ISR

Wow, fantastic! Even on PSG I could really hear it quite clearly, especially number 0

The player is linked to the isr resolution (50/60hz), so unless of linesplits, there is no option for temporal dithering.

And I meant just normal 50/60 Hz interrupt speed, nothing faster.

I know it is changing frequencies. But I meant, for example, if the "target" signal has four constant frequencies, 1, 2, 3 and 4, with respective amplitudes 10, 8, 5 and 4, then you could for example, instead of only playing frequencies 1, 2 and 3, and not frequency 4 at all, dither between frequencies 3 and 4 with the third oscillator, so that both of them get at least some "air time".

Any frequencies that exist in the original (target) signal, but you do _not_ play during a frame, should be added to your "error". And try to diffuse the error over time, just like in error-diffusion dithering with graphics. Of course you should use some kind of temporal windowing, maybe something like 3-4 frames, and only try to make up for at most 10 of the loudest frequencies. Or something. And since you have not just 1, but 3 or 5 oscillators to "paint" with at any given time, you'd try to minimize the error using all of those together. For each frame, the "encoder" should try to find out the combination of 3 (or 5) frequencies that minimizes the cumulative error. And use coefficients when calculating the error diffusion, Floyd-Steinberg style.

Another way to look at the error is "frequency debt". You have very limited resources you try to balance. Or a frequency hospital. You have patients who are badly wounded, and try to let as few of them die as possible.

Just ideas that came to mind in a minute.

Like I said, I don't know what it would sound like, since I haven't tried it, but vsync-rate dithering works with chord arpeggios in music. So why not with speech. Noise can make up for missing signal segments, at least in some cases. And if you play it back with loudspeakers in a room (and not with headphones), the pitch segments will keep sounding (echoing) a short while because of room reflections and speaker resonance etc., overlapping with each other, even when using only one voice. You could have many more than three or five "virtual oscillators"?